1. Field of the Invention
This invention relates in general to a spark ignition reciprocating internal combustion engine having an intake section defined within each combustion chamber, wherein the intake section facilitates formation of a stratified charge of a rich fuel-air mixture near the spark plug. The invention further relates to internal combustion engines, of either the four-stroke cycle or two-stroke cycle type, which operate on liquid or gaseous fuels, preferably hydro-carbons of various compositions.
2. The Prior Art
Over more than three decades, internal combustion engine configurations have been known which utilize charge stratification in the combustion chamber in connection with spark ignition, to enable engine operation using excess air. It is well known that such internal combustion engine operation has several advantages over the usual spark ignition engines which operate with a homogeneous air-fuel mixture. These advantages include, for example:
1. Lower combustion process temperatures, especially at partial load, as the fuel-air mixture may be leaner than the chemically correct mixture. As a result, the heat loss to the combustion chamber walls may be reduced. PA1 2. Increased thermal and chemical efficiency as the thermodynamic process using excess air more closely approximates the pure air cycle and, furthermore, perfect combustion with excess air is possible. PA1 3. Less or no dissociation of combustion products as compared to a conventional spark ignition engine, due to the lower combustion temperatures which result from the excess air supply. PA1 4. Lower engine pumping losses, since little or no throttling of the intake air is required and, accordingly, the engine operation may be controlled chiefly through mixture adjustment. PA1 5. The charge stratification, i.e., keeping the rich mixture close to the spark plug, makes it possible for the engine to operate as a multi-fuel engine, without knocking even when low octane fuels are used. PA1 6. Considerably reduced emission of pollutants in the exhaust gases, especially carbon monoxide and nitrogen oxides, resulting from the lower combustion temperatures and for the more perfect combustion resulting from use of excess air.
Some known charge-stratified internal combustion engines are the following: (I) Broderson's Stratified Charge Engine, USA, 1952; (II) Texaco Combustion Process by E. M. Barber, USA, 1949; (III) J. Wizky's Stratified Charge Engine, USA, 1949, and (IV) Hesselmann's Oil Engine, Sweden, 1934. To achieve a charge stratification, i.e., a richer fuel-air mixture in the vicinity of the spark plug, the four combustion systems mentioned above have the following common characteristics: (a) high-pressure fuel injection into the combustion chamber at the end of the compression stroke, shortly prior to the initiation of the spark ignition, and (b) transfer of the rich fuel-air mixture to the spark plug by a rotating air charge.
One inherent disadvantage of these characteristics, especially with the combustion processes utilized in engines I, II, and IV, stems from the necessity to control the injection and ignition timing according to the engine load and speed. Moreover, the injection and ignition timing must be matched under any operating conditions. The only combustion process producing a richer mixture in the center of the combustion chamber, at the spark plug, independent of engine load and speed, is utilized in engine III. Of the combustion processes employed in the several engines I-IV, therefore, only that of engine III allows the injection and ignition timing to be selected independently of engine load and speed, but even then only within certain limits.
These and other shortcomings of the prior art are overcome by the present invention.